Additional Content Pack 3 will give you the same kind of content as Additional Content Pack 1 and Pack 2, a new dungeon change, new plans, a new Colosseum battle, and another increase to your character's maximum level cap.
I was never a fan of grinding out levels far beyond what is needed to complete a game, especially in an easier game like this that doesn't require it, but it is something that interests many JRPG players, if you are that kind of player then this will likely be something for you. With a price of only $1 you can at least buy it for a reasonable amount.
The included extra, Change Dungeon: Iris Field, will also give you a decent place to level up your characters. Worth it for fans of grinding levels and big fans of the game but this is not needed for most people who just want to complete the game for the story or characters.

77

Nice addition to the game

TokiTheCleaver

12/21/2015

This DLC adds new content to the base game, that is 4 plans (all for rings), along with a Dungeon "Iris Field". It also increases the level cap by 300, giving some more room and length to the game.
The new Colosseum Battle is "meh" at best, but the rest is great. In my opinion, this DLC packs enough to satisfy its price, but you should probably wait for a replay to buy and play it, as it changes the original content a bit.